This invention relates to a method and apparatus for directing electromagnetic energy, and in particular, but not exclusively, to such a method and apparatus for use in the fields of defence as a directed energy weapon, means of illumination for an active sensor and/or guidance system, countermeasure, or to ignite a fusion weapon; power transmission by means of a beam; propulsion by means of a beam or inertial fusion; power generation from inertial fusion; or telecommunications.